Czorian Siege is an arcade action game similar to Space Invaders. You control a spaceship at the bottom of the screen and need to defend yourself from the waves of attacking enemies. Each time you clear the screen of all enemies, you move on to the next, more difficult round. Each round also has a time limit, if the time limit expires but you still haven't destroyed all of the enemies, you will move on to the next round anyway. There are eight different types of enemy ships that will appear, plus on many of the screens there is a shield which you will need to shoot through before you can hit the various ships. You begin the game with four lives, and additional lives can be earned for every 5,000 points. The game ends when you have lost all of your lives.